1. Field of the Invention
Embodiments relate to an apparatus and method for controlling an orbiting satellite, and more particularly, to a method of calculating a line rate to adjust a scanning speed of a low earth orbit (LEO) satellite that scans a planetary surface.
2. Description of the Related Art
An image acquisition operation performed by a multi-purpose satellite may be broadly classified into strip imaging, stereo imaging, multi-point imaging and wide area imaging. The wide area imaging may refer to scanning a ground in an arbitrary direction.
To perform the wide area imaging, the multi-purpose satellite may use a push broom camera. The push broom camera may scan objects on a ground by looking over the objects as if sweeping with a broom. Accordingly, the wide area imaging may be performed by setting, in advance, a speed at which a single line of an image is scanned to correspond to an orbital velocity of the multi-purpose satellite. A line rate may refer to a number of image lines scanned for 1 second, and may be calculated using Equation 1 shown below.
                              Line          ⁢                                          ⁢          rate                =                              Ground            ⁢                                                  ⁢            velocity                                G            ⁢                                                  ⁢            S            ⁢                                                  ⁢            D                                              [                  Equation          ⁢                                          ⁢          1                ]            
Referring to Equation 1, a ground velocity represents a ground velocity of a line of sight (LOS) of a satellite camera of the multi-purpose satellite, and a ground sample distance (GSD) represents a size of a pixel scanned by the satellite camera and projected onto the ground. A value of the line rate may be determined based on attitude and position of the multi-purpose satellite.
A scheme of calculating a line rate during wide area imaging in a related art is performed based on only a distance from a multi-purpose satellite to a scanning ground point and a pitch angle corresponding to the attitude of the multi-purpose satellite. However, the scheme has a limitation in that the scheme is merely applicable to an example in which a speed direction and a scanning direction of the multi-purpose satellite are the same and that it is impossible to apply the scheme to wide area imaging performed in an arbitrary scanning direction.